Cutting insert and power skiving tool

Abstract

Herein a cutting insert for a power skiving tool is disclosed. The cutting insert includes an insert body having a bottom surface extending in a first plane, and a body axis extending substantially in parallel with the first plane. The insert body has a cutting end portion and opposite thereto, an abutment surface. The abutment surface extends substantially perpendicularly to the body axis and to the first plane. The cutting end portion is provided with a first and a second cutting edge, the first cutting edge and the second cutting edge being directed in a same cutting direction. Herein, further a power skiving tool including such cutting inserts is disclosed.

The invention claimed is: 
     
       1. A cutting insert for a power skiving tool, the cutting insert comprising:
 an insert body having a bottom surface generally extending in a first plane and being configured to abut against a corresponding surface of the power skiving tool, an upper surface extending opposite to the bottom surface, and a body axis extending substantially in parallel with the first plane, wherein as seen along the body axis the insert body includes a cutting end portion and opposite thereto an abutment surface configured to abut against a corresponding surface of the power skiving tool, wherein the abutment surface extends substantially perpendicularly to the body axis and to the first plane, wherein the cutting end portion is provided with a first cutting edge and a second cutting edge, the first cutting edge and the second cutting edge being directed in a same cutting direction, wherein the first cutting edge extends along an edge portion of the upper surface and the second cutting edge extends in a second plane, the second plane being substantially parallel with the first plane and extending between the upper surface and the first plane, and as seen along a normal to the first plane at least a portion of the second cutting edge extends from the insert body beyond the first cutting edge. 
 
     
     
       2. The cutting insert according to  claim 1 , wherein the upper surface extends substantially in parallel with the first plane. 
     
     
       3. The cutting insert according to  claim 1 , wherein each of the first and second cutting edges includes a nose edge portion, a first lateral edge portion, and a second lateral edge portion, the nose edge portion merging into the first lateral edge portion and the second lateral edge portion. 
     
     
       4. The cutting insert according to  claim 3 , wherein each of the first and second cutting edges has a first ending edge portion and a second ending edge portion, wherein the first lateral edge portion extends at an acute angle to the body axis and merges into the first ending edge portion and the second lateral edge portion extends at an acute angle to the body axis and merges into the second ending edge portion, and wherein at least a portion of the first ending edge portion extends at a less acute angle to the body axis than the first lateral edge portion and at least a portion of the second ending edge portion extends at a less acute angle to the body axis than the second lateral edge portion, such that the first ending edge portion and the second ending edge portion are arranged to cut tip portions of teeth. 
     
     
       5. The cutting insert according to  claim 4 , wherein each of the first and second cutting edges is configured to cut with the first ending edge portion, the first lateral edge portion, the nose edge portion, the second lateral edge portion, and the second ending edge portion in one cutting pass on a workpiece. 
     
     
       6. The cutting insert according to  claim 3 , wherein the first lateral edge portion has a convexly shaped portion adjacent to a concavely shaped portion and the second lateral edge portion has a convexly shaped portion. 
     
     
       7. The cutting insert according to  claim 1 , wherein the second cutting edge is sharper than the first cutting edge. 
     
     
       8. The cutting insert according to  claim 1 , wherein a wedge angle of the first cutting edge is less than a wedge angle of the second cutting edge. 
     
     
       9. The cutting insert according to  claim 1 , further comprising a third cutting edge, wherein the third cutting edge extends in a third plane, the third plane being substantially parallel with the first plane and extending between the second plane and the first plane, and wherein the third cutting edge includes a nose edge portion, a first lateral edge portion, and a second lateral edge portion, the nose edge portion merging into the first lateral edge portion and the second lateral edge portion. 
     
     
       10. The cutting insert according to  claim 1 , wherein as seen along the body axis opposite to the cutting end portion, the insert body includes a positioning end portion configured to position the cutting insert in a power skiving tool, the upper surface being delimited by two right angle corner portions in the positioning end portion, wherein an edge of the abutment surface forms an edge of the two right angle corner portions, and wherein only the cutting end portion is provided with cutting edges. 
     
     
       11. The cutting insert according to  claim 10 , wherein the positioning end portion has a substantially rectangular shape as seen along the normal of the first plane, and wherein the positioning end portion has a width which is wider than a width of the cutting end portion, in a direction perpendicularly to the body axis and in parallel with the first plane. 
     
     
       12. The cutting insert according to  claim 10 , wherein a through-hole extends through the insert body between the bottom surface and the upper surface of the insert body, at least partially in the positioning end portion. 
     
     
       13. The cutting insert according to  claim 1 , wherein the bottom surface is provided with at least one ridge and/or at least one groove extending in parallel with the body axis and being configured to mesh with at least one corresponding groove and/or ridge of a power skiving tool. 
     
     
       14. A rotatable power skiving tool comprising:
 a generally circular tool body having a center axis about which the power skiving tool is rotatable, the tool body including a number of peripherally arranged insert seats arranged on one side of a reference plane, the reference plane extending perpendicularly to the center axis, wherein the insert seats face away from the reference plane; and 
 a cutting insert arranged in each of a respective insert seat, the cutting insert including an insert body having a bottom surface generally extending in a first plane and being configured to abut against a corresponding surface of the power skiving tool, an upper surface extending opposite to the bottom surface, and a body axis extending substantially in parallel with the first plane, wherein as seen along the body axis the insert body includes a cutting end portion and opposite thereto an abutment surface configured to abut against a corresponding surface of the power skiving tool, wherein the abutment surface extends substantially perpendicularly to the body axis and to the first plane, wherein the cutting end portion is provided with a first cutting edge and a second cutting edge, the first cutting edge and the second cutting edge being directed in a same cutting direction, wherein the first cutting edge extends along an edge portion of the upper surface and the second cutting edge extends in a second plane, the second plane being substantially parallel with the first plane and extending between the upper surface and the first plane, and as seen along a normal to the first plane at least a portion of the second cutting edge extends from the insert body beyond the first cutting edge. 
 
     
     
       15. The rotatable power skiving tool according to  claim 14 , wherein a seat bottom surface of each insert seat, in a direction radially from the center axis, forms an angle (γ) within a range of 2-15 degrees, preferably approximately 10 degrees, with the reference plane. 
     
     
       16. The rotatable power skiving tool according to  claim 15 , wherein the seat bottom surface of each insert seat, in a direction tangential to the generally circular tool body, forms an angle (δ) of a maximum of 30 degrees with the reference plane. 
     
     
       17. The rotatable power skiving tool according to  claim 15 , wherein the seat bottom surface of each insert seat is provided with ridges and grooves. 
     
     
       18. The rotatable power skiving tool according to  claim 14 , further comprising an adjusting mechanism for adjusting a radial position of the cutting insert arranged radially inside of each insert seat, the adjusting mechanism abutting against the abutment surface of the cutting insert. 
     
     
       19. The cutting insert according to  claim 12 , wherein the through-hole extends through the insert body between the bottom surface and the upper surface of the insert and is located entirely in the positioning end portion. 
     
     
       20. The rotatable power skiving tool according to  claim 14 , wherein a seat bottom surface of each insert seat, in a direction radially from the center axis, forms an angle (γ) of approximately 10 degrees with the reference plane. 
     
     
       21. The rotatable power skiving tool according to  claim 15 , wherein the seat bottom surface of each insert seat, in a direction tangential to the generally circular tool body, forms an angle (δ) of approximately 20 degrees with the reference plane. 
     
     
       22. The rotatable power skiving tool according to  claim 16 , wherein the seat bottom surface of each insert seat is provided with ridges and grooves.